Inhibiting influenza virus replication and inducing protection against lethal influenza virus challenge through chitosan nanoparticles loaded by siRNA

Influenza virus causes a highly contagious viral respiratory tract infection with potentially fatal outcomes in humans and animals. There is now widespread influenza virus resistance to commercial drugs due to the genetic diversity of virus. Therefore, new therapeutic formulation needs to be developed. Chitosan/siRNA nanoparticles were generated as a new therapeutic approach against influenza virus infections both in vitro and in vivo. Designed siRNA against influenza nucleoprotein was formulated in chitosan polymer as siRNA/chitosan nanoparticle complex. Particle size and zeta potential of the nanoparticles were measured by dynamic light scattering. The uptake of labeled siRNA into Vero cells was visualized using fluorescence microscopy. Nanoparticle-mediated knockdown of enhanced green fluorescent protein (EGFP) was analyzed and quantified by flow cytometry in Vero cells. Results of the in vitro study showed that chitosan/siRNA nanoparticle was efficiently uptaken by Vero cells, leading to inhibition of influenza virus replication. Furthermore, nasal delivery of siRNA by chitosan nanoparticle complex has antiviral effects and significantly protected BALB/c mice from a lethal influenza challenge. These findings suggest that chitosan nanoparticle equipped with siRNA is a promising system for controlling influenza virus infection.